1. Technical Field of the Invention
This invention relates to the manufacture and isobutylene-assisted purification of methyl tertiary butyl ether. More particularly, this invention relates to a process for the manufacture of methyl tertiary butyl ether from tertiary butyl alcohol and methanol and to the purification of a methanol-contaminated methyl tertiary butyl ether intermediate product formed during the process; the intermediate product being purified by counter-current contact with water in an extraction tower, wherein isobutylene is added to the extraction tower to assist in the formation of a raffinate composed of methyl tertiary butyl ether, isobutylene and residual water and an extract comprising methanol, residual isobutylene, residual methyl tertiary butyl alcohol and water.
Still more particularly, this invention relates to a process for the manufacture of methyl tertiary butyl ether from tertiary butyl alcohol and methanol and to the purification of a methanol-contaminated methyl tertiary butyl ether intermediate product formed during the process; the intermediate product being purified by counter-current contact with water in an extraction tower, wherein isobutylene is added to the extraction tower in admixture with the methanol-contaminated methyl tertiary butyl ether to assist in the formation of a raffinate composed of methyl tertiary butyl ether, isobutylene and residual water and an extract comprising methanol, residual isobutylene, residual methyl tertiary butyl ether and water.
Even more particularly, this invention relates to a method of purification of methanol-contaminated methyl tertiary butyl ether by counter-current contact with water in an extraction tower, wherein isobutylene is separately added to the extraction tower below the point at which the methanol-contaminated methyl tertiary butyl ether is introduced in order to selectively strip at least a portion of the residual methyl tertiary butyl ether from the extract.
2. Prior Art
In U.S. Pat. No. 4,144,138 (1979) to Rao et al., there is disclosed a method for recovering methyl tertiary butyl ether from etherification reaction effluent by azeotropic distillation to recover methanol-ether azeotrope overhead which is water-washed to give pure ether raffinate, the latter being azeotropically distilled to yield ether-methanol overhead which is recycled to water washing.
The preparation of methyl tert-butyl ether from methyl and tert-butyl alcohols is discussed in S. V. Rozhkov et al., Prevrashch Uglevodorodov, Kislotno-Osnovn. Geterogennykh Katal. Tezisy Dokl., Vses. Konf., 1977, 150 (C. A. 92:58165y). Here the TBA and methanol undergo etherification over KU-2 strongly acidic sulfopolystyrene cation-exchangers under mild conditions. This reference contains data on basic parameters of such a process.
Liquid-liquid extraction is described in an article by Cusak et al., "A Fresh Look at Liquid-Liquid Extraction" (Chemical Engineering, March 1991, pp. 132-138) and an article by Cusak et al. also entitled "A Fresh Look at Liquid-Liquid Extraction" (Chemical Engineering, February 1991, pp. 66-76).